Two issues regarding C5

[atr]

Yesterday, I've noticed that the temperature gauge in the vehicle is rising and eventually it climbed up to the red zone and the "stop" lamp lit. it occurred while I was standing at a traffic light. since I was on a highway, I couldn't stop on the spot and while continuing to drive, the temperature began to decrease, I kept on driving and the needle was at the normal position. when I reached home and stopped the vehicle. I've noticed that the fan doesn't working (it's usually keeps working after the car is parked). any clue where to look?
The second question is regarding the A/C. I've noticed that it doesn't provides cool air when the vehicle is not driving, e.g, at a traffic light. when driving, it works fine and delivers nice cool air.
Looking forward for your advice/s.

[teuski]

My experience is with MK1:

There are two resistor for the fan, one for high and other for low speed. They are located in the black box on the right side of the radiator (looking from front) and look like this. The other one is brown color.

There is a thermal fuse (185 Celsius, the orange component in the picture) next to the resistor which is usually the point of fault. When a resistor (or fuse) is blown the respective speed of the fan does not work. I suppose the AC ceases to work while stopped because the cooling fan doesn't run.

The heat fuse needs to be soldered to the resistor wire. Pay attention to its distance from the resistor itself so it won't burn too easy.

[atr]

Teuski, thanks for the detailed reply. do you know if the thermal fuse is sold separately? if so, can it be found at a Citroen spare parts dealership? or it is sold only as a complete assembly?
Btw - you've mentioned that it's rated 185Deg. C. is it the heat that the resistor produces? (I assume that the coil is the resistor).

[Paul-R]

My experience is that over the winter the fan is not used to cool the radiator as the forward movement is enough. After a while the fan seizes and, in my case, the maxi fuse blew. I replaced the fan unit (I wasn't able to free it off) and fuse and all worked. I didn't need to change the resistor packs.

The AC won't operate unless the fan is working. In fact when the AC is in use the fan operates all the time regardless of the temperature of the coolant. It's recommended that you operate the AC every so often over the winter so that the compressor doesn't seize up. This has the secondary effect that the cooling fan would then operate and this would (should!) extend its life,

[Stickyfinger]

Use AirCon in the winter to de-humidify the car.....it prevents misting up in the morning.

[atr]

HI
Thanks for your replies.
I've checked this morning after a short ride and I've seen that the fan is working. I assume that it was running on the regular speed since it was a short ride and the temperature gauge didn't move beyond the middle of the scale. so, if I got it right so far, it might be that the fan is not running at the top speed when needed. could you please tell me where the high speed fuse located?
Thanks.

[teuski]

If low speed works, then it's probably the high speed resistor. Can't remember which one is which.

The thermal fuse is not sold as a Citroën spare part but can be found in stores that sell electronics components. I have used a 185 Celsius fuse which should be close to original. It shouldn't matter if it's a bit hotter, the purpose is to protect the resistor itself from overheating. That number is the temperature that burns the fuse. As you can see it is close to the resistor spiral, and when it heats too much the fuse next to it heats up to the limit and burns.

What a great idea, put a thermal fuse to protect the part from burning, but burning the fuse effectively breaks the whole part. I doubt that official workshops fix them by changing the fuse...

[atr]

Paul-R, you are saying that turning on the AC connects the fan, regardless of the temperature, which makes sense. I assume that the fan operates at it's low speed and the high speed kicks in according to the rise of the temperature and so, I guess that there is the problem, that the high speed doesn't working. is there a way to check if the fan motor is working? is there a relay that turns on the high speed and if so, could you tell me where it is located? it can be bypassed to make sure that both speed are working.
Btw- in the drivers handbook- only one fuse for the fan is mentioned. it's named F1, 20A rated. since you've mentioned that on your vehicle the "maxi fuse blew", I assumed that there is a separate fuse for each speed.
Thanks again.

[Paul-R]

I could never figure out the resistor combinations for the fan. Certainly one is used to reduce the speed but what is the second one for? It's unclear whether there is an intermediate speed as well - perhaps some variants have this. You could usefully use a Lexia, Diagbox or top end generic code reader to operate the fan and see whether both speeds are working. Maybe on some cars there are three speeds to test but not mine.

I also had the same problem with a seized fan on the Xsara. The fix was a bit more here than the C5. I had to replace one of the resistors as well and there was corrosion on a lot of the electrical connections. One of the relays was so bad that a terminal had corroded away and broke off.

[Paul-R]

Paul-R, you are saying that turning on the AC connects the fan, regardless of the temperature, which makes sense.

Yes, that's exactly it.

I assume that the fan operates at it's low speed and the high speed kicks in according to the rise of the temperature and so, I guess that there is the problem, that the high speed doesn't working. is there a way to check if the fan motor is working? is there a relay that turns on the high speed and if so, could you tell me where it is located? it can be bypassed to make sure that both speed are working.

Not sure what speed it comes in at but what you say makes sense. There are several relays which work the different speed combinations. The resistors are in a longish plastic enclosure. If you are standing in front of the cat this is on the right of the radiator panel. You may have to remove the bumper to get at this I can't remember. It certainly makes things easier. I can't remember if the relays are here as well but they may be - or I could be mixing up the location with the Xsara!

Btw- in the drivers handbook- only one fuse for the fan is mentioned. it's named F1, 20A rated. since you've mentioned that on your vehicle the "maxi fuse blew", I assumed that there is a separate fuse for each speed.
Thanks again.

I'm fairly sure there's no separate fuse for the different speeds. Your maxi fuse is obviously OK if you're getting at least one speed. I would look very closely at all the connections for corrosion and, if the relays are with the resistors, ditto the connections there. It's entirely possible the relays are located with the fuse box and if so that's an different world of difficulty.

[teuski]

is there a way to check if the fan motor is working?

Didn't you just say you verified the fan is working at least at one speed?

There is no need to remove the bumper to get at the resistors.
I don't know why there is a resistor for full speed too, but there is and if it's broken full speed doesn't work.

As i said i was speaking about mk1.
I just checked Citroën Service and mk2 with the EW10A seems to have different looking setup without the resistors. There seems to be one relay next to the fan that changes from 45A to 50A at RPO 11284 (10/2007).

[Paul-R]

Yes, this seems to indicate that the fan is working at some level.

I've checked this morning after a short ride and I've seen that the fan is working.

I find it curious that it's a slower speed is working but not the top speed. My old C5 worked for ages with just the top speed only.

...could you please tell me where the high speed fuse located?

As I said, I don't think there is a separate fuse.

[atr]

You could usefully use a Lexia, Diagbox or top end generic code reader to operate the fan and see whether both speeds are working. Maybe on some cars there are three speeds to test but not mine.

Gladly I've connected my Lexia in order to carry out the test but unfortunately I didn't found how to control/operate the cooling fan from it. I've navigated on all(?) the possibilities, but wasn't able to find it. if you know how to reach it, please let me know.
Thanks.

[white exec]

For some years, the typical arrangement for a single fan is:
- One resistor in circuit for Lo speed, switched on by a relay
- Second relay (when triggered) brings on Hi speed, and feeds the fan motor direct (i.e. by-passes or shorts out dropper resistor)

And for twin fan models:
- Three relays
- No resistor
- Fans operate in series for Lo speed
- Fans operate in parallel for Hi speed

For both arrangements, turning on AC automatically brings fan(s) on at Lo speed, irrespective of temperature.
Both arrangements just have two supply inputs (i.e. to the respective relays) - Run at Lo, Run at Hi.
These inputs come either from the engine ECU, or (depending on model) from a two-stage 'thermo switch', usually fitted in the radiator side tank.

The appropriate circuit diagrams for C5 will show all this clearly.

The small thermal fuse (usually tapered end, and doesn't matter which way round it's fitted) is there simply to cut the fan supply should the high-wattage dropper resistance overheat, possibly as a result of fan motor short/overload/seizure. Without this thermal fuse, there could be enough heat generated in the resistor to start a fire. Twin-fan models have the advantage that there is no need for a dropper resistance.

[Paul-R]

Sorry, I'm on holiday without my Lexia laptop so can't check anything out. Hopefully someone else can find where it is for you.